enabling mistral training by adding mistral template

[Jayantverma2]

Pull Request Description

Changes Made

Added conv_biomistral template for mistral training in the ./llava/conversation.py

Details

• Updated the file to include the conv_biomistral template.
• This template follows the mistral format and includes the necessary system and user/assistant roles.

Purpose

This pull request aims to provide a template (conv_biomistral) suitable for mistral training. It follows the specified format and should enhance the capabilities of the training process.

Checklist

• I have tested the changes locally.
• The code follows the project's coding standards.

[Jayantverma2]

this will enable training with mixtral, biomistral, and mistral

[aliencaocao]

why not use mistral_instruct?